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The BADC-CSV Format: Meeting user and metadata requirements
No full textThe 2007 British Atmospheric Data Centre (BADC) Users Survey examined the skill base of the BADC’s user
community. Results indicated a large proportion of users who were familiar with data held in ASCII formats
such as comma-separated variables (csv) and there was a high degree of familiarity with spreadsheet
programmes (e.g. Excel) for data analysis purposes. These result, combined with the experiences of the BADC
staff dealing with user enquiries and assisting data suppliers in preparing data for submission, and the metadata
requirements of the BADC, highlighted the need for a new ASCII format to be generated. The BADC-CSV
format adheres to metadata conventions covered by the NASA-Ames and netCDF formats, the CF and Dublin
Core metadata conventions, the ISO19115 standard and the metadata requirements of the BADC and its sister
data centres within the Natural Environment Research Council (NERC). The format meets end user and data
supplier requirements by being a native format for spreadsheet software as well as other commonly used data
production and analysis tools (e.g. IDL, MatLab). This paper presents the requirements for the format resulting
from the 2007 user survey and data centre requirements, describes the structure of the format and demonstrates
the format through short examples. Finally ongoing work to further develop the format is discussed
Internal variability in the moist African easterly Jet - African easterly wave system
No full textA crucially important component of the West African Monsoon (WAM) and its associated rainfall variability, is the African easterly jet-African easterly wave (AEJ-AEW) system. Despite this, the system continues to pose a tough challenge for General Circulation Models (GCMs) to simulate realistically given the many physical processes involved, and given the multitude of spatio-temporal scales that they act over.
For the West African population, any intra-seasonal rainfall variability impacts severely on the local agricultural and water resources, with equally severe consequences on health. This is especially true for the population living in the semi-arid Sahel region which endures the full impact of the AEJ-AEW system. Improved skilful prediction of the monsoon rains over longer time-scales would be of enormous benefit, aiding in the mitigation of high impact situations events such as the flooding during the summer of 2007, and the drought conditions of the last few decades.
Here, the African Easterly jet - Easterly wave (AEJ-AEW) system was explored in an idealised model. Prescribed zonally symmetric surface temperature and moisture profiles determine the AEJ which becomes established through meridional contrasts in dry and moist convection.
Importantly, moist AEWs were characterized by intermittent periods of growth and decay, with growth preceded by increased mean rainfall and later, weakening AEJs. These dependencies established an internal 8-10 day variability, consistent with intra-seasonal observations of 9-day rainy sequences. The observed 8-10 day cycle of rainy sequences related to the natural life cycle of the moist AEW and its interaction with the AEJ, the upper levels and the precipitation. This is a significant result from the moist life cycle as it offers a new view of the moist AEW life cycle and provides an alternative explanation for the observed intra-seasonal variability of the precipitation over NW Africa
